Elastic properties of silicon dioxide films deposited by chemical vapour deposition from tetraethylorthosilicate

Dielectric silicate glass films have been obtained from tetraethylorthosilicate using both low-pressure chemical vapour deposition and plasma-enhanced chemical vapour deposition. The elastic properties of these films, which are deposited on (100)-Si wafers, have been studied by means of the Brillouin light scattering technique. The phase velocity of both the surface Rayleigh wave and the longitudinal wave in the film material have been measured and the two independent elastic constants c(11) and c(44) evaluated, This permitted us to derive the values of Young's modulus and Poisson's ratio which are useful quantities for the modelling of the elastic properties of multilevel structures used in electronics. Moreover, the substrate curvature method has been exploited in the case of the PECVD film, to study the evolution of the stress during subsequent thermal cycles. The values of the thermal expansion coefficient and of the water diffusion coefficient have thus been determined. (C) 1997 Elsevier Science S.A.